1. Field of the Invention
The present invention relates to a flash monitor for determining the excitation of a flash tube in photography or the presence of flashing light such as that produced by an emergency vehicle and, more particularly, to a flash monitor alarm system for determining whether the inductive pulse associated with a photographic flash tube includes a true inductive flash tube discharge pulse, or whether the flash tube failed to fire properly or at all, and to a flash monitor alarm system that can detect emergency vehicle flashes even in the presence of strong ambient light.
2. Description of Related Art
The possibility of undetected flash failure in photography is increased as lighting setups become more complex or spread over larger studio set and location setups. In a tight, high-pressure shoot it is easy to miss a dead light.
The photographic flash monitor art is generally cognizant of flash monitors which utilize photosensors to detect light. While a "flash ready" light gives some assurance that the strobe fired, the assurance is not all it suggests. A ready light merely indicates that the capacitors have charged, which can happen even if the tube itself is defective. Although a few flash monitors exist, the art is still seeking an inexpensive, convenient, easily-mounted flash monitor alarm system capable of reliably distinguishing between a true inductive flash tube discharge pulse which is associated with the proper firing of a flash tube and a high-voltage trigger pulse not followed by a discharge pulse, such a trigger pulse being associated with a flash tube misfire.
On the other hand, emergency vehicle flashing lights are best detected by photodetectors. The prior art has employed photodetector systems that are able to detect flash patterns that are produced by special optical transmitters to cause traffic signals to respond to emergency vehicles. For example, see U.S. Pat. No. Re. 28,100 to Long and U.S. Pat. No. 4,234,967 to Henschel. While the prior art recognized the importance of a relatively complex transmitter/detector systems for use in traffic signal control, there remains a substantial need for a simpler system to warn drivers of individual cars or trucks that an emergency vehicle is operating in the vicinity. Modern vehicles have been made almost soundproof. Furthermore, vehicle sound systems including CD players, stereos, and cellular telephones interfere with a driver's ability to hear emergency vehicle sirens. During the daylight hours emergency vehicle flashers may not be easily perceived.